The purpose of this proposal is to assess the role of prostaglandins in macrophage activation. To accomplish this we will determine the effect of prostaglandin on the functional capacity of operationally defined stages of macrophage activation. We will also determine the effectof prostaglandin on the induction of primed noncytolytic macrophages and cytolytic macrophages by lymphokine, LPS or both. Our experiments are designed to test the hypothesis that prostaglandins effect the macrophage differently depending on its stage of prior activation. We propose to 1) examine the effect of prostaglandins on mononuclear phagocytes at different levels of activation; 2) determine the effects of agents which alter cyclic nucleotides on the functional capacity of mononuclear phagocytes and 3) determine the effects of agents which activiate macrophages on prostaglandin metabolism of these cells and the effect of prostaglandin on activation.